I wonder if you’ve been asked that question. “Why did Mary have to be a virgin?” I wonder how you would answer it? The liberal and sceptical answer is that he didn’t and he wasn’t. There was no literal virgin birth. The argument is that Jesus was just an ordinary child born out of wedlock, with questions about his legitimacy and the early church had to develop a tradition to explain it away. So, they took an Old Testament prophecy and misunderstood it. Isaiah 7:14 says:
14 Therefore the Lord himself will give you a sign. Behold, the virgin shall conceive and bear a son, and shall call his name Immanuel.
Except that the Hebrew word translated “virgin” doesn’t have to mean that. It simply could refer to a young woman or girl. It was when the text was translated from Hebrew to Greek that the Greek word for “virgin” rather than simply “young woman” began to be used. The original prophecy was simply saying that a younger woman, around about the time of the prophecy would become pregnant.
Certainly, in context you would expect that the prophecy referred to an immediate event and that does seem to be how Scripture at times works with immediate and later/greater fulfilment. However, I think there is a problem with the assumption that the virgin birth was all a big misunderstanding/translation error. The problem is that those who translated the text will have fully understood what they were doing and the range of options within the semantic range of the Hebrew word. There is a conscious decision to go with “virgin.” I suspect that tells us something. I would suggest that the translators were aware that the full, grander implications of the prophecy depended on something more than someone becoming pregnant through natural means. They knew that it was likely that a younger unmarried girl would be a virgin and so they chose the Greek word with care.
Most commonly when people explain why the virgin birth was necessary, they will argue that it was important if Jesus was to be both fully God and fully man and if he were to be sinless. The argument then is that sinful nature is inherited through the male line because we sinned in Adam. If Joseph had been Jesus’ dad then he would have inherited his sin from him.
I think there are a couple of problems with this. First of all, I think that unintentionally, it does risk implying that Jesus wasn’t completely human, that he only received the aspects of his human nature passed on from one side, Mary’s. Whilst Jesus did not sin and was not under the penalty of sin, so that he did not receive a sinful nature, he did receive a full human nature subject to all of the effects of the fall including death. Secondly, I would argue that it takes us in the direction of the trap that the Catholic Church fell into. So concerned were they to protect Jesus from inheriting and getting contaminated by sin that they argued that not only must he be born of a virgin but also his mum too. That’s how we end up with the doctrine of the immaculate conception.
Thirdly, I would argue that this isn’t how Scripture or we properly understand the idea that all sinned in Adam. It’s not that Adam passes on sin genetically, it’s that are in him if we are not in Christ. That Adam is our federal head and so there is a sense that we were included in with his sin. The consequence of this is that when we think of inheritance/descent, we don’t just think about physical lineage but the legal line too. You will see in Jesus’s family tree some twists and turns caused by levirate marriages where the younger brother steps in father a child when his brother dies. In those cases, the child remained the legal heir of the older brother. In other words, Jesus does not have to be Joseph’s physical son in order to legally inherit from him.
No, Jesus is free from Adam’s sin not because he didn’t physically inherit his nature but because legally Jesus always was and is greater than Adam so that he owes nothing legally to Adam. Jesus has never been “in Adam.”
Finally, however, I think the main reason I don’t use this argument is because Scripture doesn’t. Indeed, if we want to know why Jesus had to be born of a virgin then we should look at what the prophecy tells us and what the angel said. The answer is simply that this was the fulfilment of a prophetic sign.
In Isaiah 7, the king refuses to receive a sign from God both that judgement and salvation is coming. So God insists that there will be a sign, the birth of Immanuel. I think we have enough reason here. The coming judgement and salvation that Jesus’ birth announced was on a greater cosmic scale than even that in Isaiah’s day. So, we have a greater sign than any seen before. The virgin conceiving is a loud and clear sign that God is acting in grace and unconditional love towards his people.
So, I don’t think we need to look hard for explanations as to why Mary had to be a virgin. Simply, we can see that God has acted clearly, unquestionably and uniquely in history to bring about our salvation. Our response should be wonder and faith.